GPS Coordinates and NMEA


#1

Hi everyone!

I´m getting NMEA string from the GPS and it says eg. my latitude is -19,58°

I know it´s wrong!

Then… I use a program called U-BLOX and it gets the same NMEA string and the -19,58° and it shows me that the Tracker I´m using is at -19,96° which is correct!

What kind of correction is U-BLOX doing? Does anybody know!?

I plugged the UART2 of the Wavecom 2501 Module in the PC serial interface. It starts to poll NMEA string and show -19,58°.

Anybody use to correct those coordinates!?

Thanks a lot!

Henrique


#2

Hello,

In the NMEA string the coordinate is in degree + minute format.
58 minute is appr. 0.96 degree. So -19 degree 58 minute (-19,58’) is
-19,96 degree.

tom


#3

Hi Tom! Thanks for the reply!

But… 58’ is a big error comparing to 96’!

When I plot it on a map I see it´s a huge error! There´s a waypoint I know it’s exact location ok? When I bring the GPS to this location and try to plot the coordnates it gives, it´s like miles away!

Do I always have to consider 96’-58’= 38’ error?

Don´t you think 0.38 degree is a little big app.?

I´m sorry if I didn´t uunderstand your point…

Thanks for the help!

Henrique


#4

Hello,

Sorry if i am understanable. That is not an error, just an other format.
One degree is 60 minute. 0,96 degree is 58 minute so comes that -19 degree 58’ minute is equal with -19,96 degree.

tom


#5

I got it now!! Thanks! That really make sense!!!

Do you know the names of these formats?

How is this conversion made? 58’ to 96’… with one point I couldn´t figure out a pattern.

Best Regards,

Henrique